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Structure covered by rocks, trees and bushes in the shape of a mountain peak

Residents concerned about safety of structure

A bizarre mountain retreat built on top of a 26-floor Beijing residential building faces demolition after complaints by residents.

The rooftop structure is covered by fake rocks, trees and bushes, and can be clearly seen from one of Beijing's busiest commuter roads in one of the city's more upmarket areas.

A CNN crew who visited the building on Tuesday saw an official government order stuck to the door giving the owner 15 days to demolish 800 square meters of the structure that have been deemed illegal.

No one answered when they knocked.

Locals say the unusual high-rise retreat has been slowly taking over the rooftop for years -- construction is said to have started in 2007 -- but is only now receiving attention after images of the unlikely extension went viral on social media.

"A lot of people have moved out from the top floors. They were afraid. They sold their apartments and got out," said Zhang Li, who lives in an apartment on the 25th floor -- one floor below the construction.

The owner of the rocky outcrop has been identified as Professor Zhang Biqing, a doctor of traditional Chinese medicine who owns a national chain of acupuncture clinics, and is a former member of a district People's Political Consultative Conference (CPPCC), according to the South China Morning Post.

"I used to worry that the house might be too much but I never expected this much attention," Zhang is reported to have told The Beijing News.

His neighbor, Zhang Li, said residents had complained many times to officials, but nothing was done to stop construction.